1. Field of the Invention
The present invention relates to a resist pattern thickening material with which thickening of the resist pattern formed in manufacturing a semiconductor device and forming a fine space pattern beyond the exposure limits of light sources of existing exposure devices are possible. The present invention also relates to a process for forming a resist pattern, a semiconductor device and a process for manufacturing the semiconductor device that utilize the resist pattern thickening material respectively.
2. Description of the Related Art
Semiconductor integrated circuits are becoming more highly integrated and LSIs and VLSIs have been put into practical use. Accompanying this trend, wiring patterns are downsized to 0.2 μm or less and the smallest patterns reaches even 0.1 μm or less. A lithographic technique is extremely important in forming fine wiring patterns. In the lithographic technique, a substrate is coated by a resist film, selectively exposed and further developed to form a resist pattern. Dry etching is carried out using the resist pattern as a mask and by removing the resist pattern thereafter, a desired pattern such as wiring pattern, etc. is obtained. In the lithographic technique, it is required for the exposure light (light used for exposure) to be a short wavelength as well as for high-resolution resist materials corresponding to the characteristics of exposure light to be developed.
However, in order for an exposure light to be a short wavelength, it is necessary to improve the exposure device which may involve enormous cost. Further, the development of new resist materials suitable for an exposure light with short wavelength is not easy.
To overcome above technical problems, a technique has been proposed wherein finer pattern is formed by using a resist pattern thickening material (hereinafter may be referred to as “resist swelling material”) with which a resist pattern formed of conventional resist material is thickened and fine space pattern can be obtained. For instance, Japanese Patent Application Laid-Open JP-A) No. 10-73927 discloses a technique called RELACS. According to the disclosure, a KrF resist pattern is formed by exposing a KrF (krypton fluoride) resist film using KrF (krypton fluoride) excimer laser light of 248 nm wavelength which is deep ultraviolet light. Thereafter, by means of a water-soluble resin composition, a coated film is provided over KrF resist pattern. The coated film and KrF resist pattern are made to interact at the interface thereof using the residual acid within the material of KrF resist pattern, and the KrF resist pattern is thickened (hereinafter may be referred to as “swelling”). In this way, the distance between KrF resist patterns is shortened (or diameter of hole is shortened in the case of hole pattern) and a fine space pattern is formed. Thereafter, a desired pattern (e.g. wiring pattern) having the same dimension as the space pattern is formed.
In RELACS technique, however, thickening is conducted by using an acid which works as a catalyzer to generate a crosslinking reaction and a large amount of thickening is obtained with a very small amount of acid therefore controlling the amount of thickening is difficult. In particular, when forming a fine pattern, the large thickening amount of resist pattern may hinder practical application and the thickening amount in the range of several dozen nm is often sufficient. However, in the resist pattern thickening technique which depends on acid diffusion from the resist pattern and resultant crosslinking reaction accelerated by an acid, fine adjustment of the thickening amount is difficult and controlling the thickening amount becomes more difficult by conditions such as temperature or density difference in patterns, etc. because it uses an acid. The density difference in patterns is the density difference between a region where resist patterns are scarce (a region where intervals of resist patterns are long) and a region where resist patterns are dense (a region where intervals of resist patterns are short).
Moreover, in RELACS technique, there are following problems. The KrF resist for use is formed of an aromatic resin composition including a novolak resin, naphthoquinonediazide resin or the like. An aromatic ring contained in the aromatic resin composition allows KrF excimer laser light (wavelength: 248 nm) to pass through, but absorbs ArF (argon fluoride) excimer laser light (wavelength: 193 nm) having a shorter wavelength than KrF excimer laser light and does not allow ArF excimer laser light to pass through. Therefore, when KrF resist is used, ArF excimer laser light cannot be used as exposure light and forming a finer wiring pattern, etc. becomes impossible. Moreover, there is a problem in the RELACS technique that the resist swelling material is effective for thickening or swelling of KrF resist but not for thickening or swelling of ArF resist. In addition, the resist swelling material used for RELACS has a problem such that even though it is effective for thickening (swelling) of KrF resist pattern, it is not effective for thickening (swelling) of ArF resist pattern.
From the standpoint of forming a fine wiring pattern, it is desirable to use exposure light of wavelength shorter than that of KrF excimer laser light (wavelength of 248 nm). For example, ArF excimer laser light (wavelength of 193 nm) may be preferable. When x-ray or electron beam having a wavelength shorter than ArF excimer laser light is used for pattern forming, however, it results in high cost and low productivity. Thus, the utilization of ArF excimer laser light is desired.
Accordingly, development of a technique which can use ArF excimer laser light as an exposure light during patterning; can easily control the thickening amount of the resist pattern which is difficult for RELACS technique; can adjust thickening amount of resist pattern without relying on the conditions such as temperature, density difference of pattern, or the like; and can easily form a fine space pattern and/or a wiring pattern at low cost is desired.
An object of the present invention is to provide a resist pattern thickening material, which can utilize ArF excimer laser light as an exposure light during patterning; which, when coated over a resist pattern, can thicken the resist pattern such as lines and spaces pattern, etc. regardless of the composition of ArF resist material, and the like; which can easily control the thickening amount of resist pattern by process condition; and which can easily and efficiently form a fine space pattern beyond the exposure (resolution) limits of light sources of the exposure devices at low cost.
Another object of the present invention is to provide a process for forming a resist pattern which can utilize ArF excimer laser light as an exposure light during patterning; which can thicken the resist pattern such as lines and spaces pattern, etc. regardless of the composition of ArF resist material, and the like; which can easily control the thickening amount of resist pattern by process condition; and which can easily and efficiently form a fine space pattern beyond the exposure (resolution) limits of light sources of the exposure devices at low cost.
Yet another object of the present invention is to provide a process for manufacturing a semiconductor device which can utilize ArF excimer laser light as an exposure light during patterning; which can form a fine space pattern beyond the exposure (resolution) limits of light sources of the exposure devices; and which can mass produce high-performance semiconductor devices having fine wiring patterns formed by using the space pattern; and a high-performance semiconductor having fine wiring patterns manufactured by the process for manufacturing a semiconductor device.